commit	1ebf615571682e3c581a4ecae0fa7f23390465ad	[log] [tgz]
author	Android Build Coastguard Worker <[email protected]>	Sat May 11 01:13:46 2024 +0000
committer	Android Build Coastguard Worker <[email protected]>	Sat May 11 01:13:46 2024 +0000
tree	8974a993893826f1fe3d6270715d6afa1df96e70
parent	4052a3c23a002a7fa935ed3df487fe97d954b0f6 [diff]
parent	003e8dd346fa39c3f1124cc4aec6c05aa0ef2cef [diff]

tree: 8974a993893826f1fe3d6270715d6afa1df96e70

README.md

pin-project

A crate for safe and ergonomic pin-projection.

Usage

Add this to your Cargo.toml:

[dependencies]
pin-project = "1"

Compiler support: requires rustc 1.56+

Examples

#[pin_project] attribute creates projection types covering all the fields of struct or enum.

use std::pin::Pin;

use pin_project::pin_project;

#[pin_project]
struct Struct<T, U> {
    #[pin]
    pinned: T,
    unpinned: U,
}

impl<T, U> Struct<T, U> {
    fn method(self: Pin<&mut Self>) {
        let this = self.project();
        let _: Pin<&mut T> = this.pinned; // Pinned reference to the field
        let _: &mut U = this.unpinned; // Normal reference to the field
    }
}

code like this will be generated

To use #[pin_project] on enums, you need to name the projection type returned from the method.

use std::pin::Pin;

use pin_project::pin_project;

#[pin_project(project = EnumProj)]
enum Enum<T, U> {
    Pinned(#[pin] T),
    Unpinned(U),
}

impl<T, U> Enum<T, U> {
    fn method(self: Pin<&mut Self>) {
        match self.project() {
            EnumProj::Pinned(x) => {
                let _: Pin<&mut T> = x;
            }
            EnumProj::Unpinned(y) => {
                let _: &mut U = y;
            }
        }
    }
}

code like this will be generated

See #[pin_project] attribute for more details, and see examples directory for more examples and generated code.

Related Projects

pin-project-lite: A lightweight version of pin-project written with declarative macros.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.